Dublin desalination is one option of ten
Dublin City Council invited views on 21 November 2008 on 10 options for augmenting existing water sources for the Dublin region, including desalination of water from the Irish Sea.No decision will be made until late 2009, at the earliest, and the public has until 27 February 2009 to give their views.
However, desalination would be the most expensive option, and the high energy cost "would have a negative environmental impact", says a consultant's report.
By 2016 the Dublin Region, which includes parts of Meath, Kildare and Wicklow will begin to need supplies from a new water source, due to anticipated growth in population in these areas. Dublin City Council appointed RPS Consulting Engineers in conjunction with Veolia Water to undertake a feasibility study of the options available for providing a new major source.
A total requirement of 300,000m³/d is the agreed planning figure for 2031 to cater for average demand/supply shortfalls and provide sufficient headroom for peak supplies, security of supply, contingencies and potential impacts of climate change.
RPS/Veolia also produced a report concentrating on desalination of seawater sourced from the Irish Sea. This would involve the construction of a major desalination facility on the east coast and a pipeline to take the desalinated water to a suitable reservoir where it would enter the supply network for the Dublin Region.
Cost estimates for the recommended works are set out below. For a desalination plant the capital and operating costs have been based on the construction of pipelines initially for the long-term capacity, while the reverse-osmosis (RO) treatment and pumping facilities are designed to match demand growth.
Calculation of average cost of water delivered to the GDA over the assumed 25-year operating period
|Capex||€ 611 million|
|OPEX||€ 336 million|
|Whole Life Cost||€ 947 million|
|WLC/Delivered Volume(€/m³)||€ 0.64/m³|
The amount of energy that would be required for the desalination treatment process and the resultant emissions of green house gases when compared with conventional treatment methods are expected to have a significant negative impact on the environment, says the report.
The proposed preliminary design contains a substantial pretreatment facility and requires a second-pass RO system to be incorporated to treat both the relatively high silt density index and boron levels present in the source water. These factors further contribute to the already anticipated high energy requirement.
In terms of the impacts on population and health, the vulnerability of the Irish Sea source to acute or chronic pollution events exposes the treatment process to risks in terms of security of supply and poor quality treated water, says the report.
The full desalination report can be found on the council's website .